Which Fire Extinguisher Should Be Used for Electrical Fires?

“For a fire involving electrical equipment, the right extinguisher matters. So does knowing when to leave it alone.”

A CO₂ fire extinguisher is commonly used for fires involving electrical equipment. It contains an electrically non-conductive gas and leaves no powder or liquid residue. You will often find one near office electrical equipment, plant rooms or other identified electrical risks.

But “electrical fire” does not tell you everything you need to know. The equipment may still be live, and the material burning could be plastic, paper, insulation or something else nearby. The first priority is to raise the alarm and get people to safety. Electrical power should only be isolated if it is safe to do so.

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What Is the Best Fire Extinguisher for an Electrical Fire?

For many ordinary workplace risks involving electrical equipment, the answer is a carbon dioxide (CO₂) extinguisher. Its extinguishing medium does not conduct electricity, and it does not leave a powder or liquid deposit across the equipment.

That makes CO₂ a common choice near electrical cabinets, machinery controls and office equipment. A premises may also need other extinguishers to cover the surrounding materials. A CO₂ extinguisher provided for an electrical risk does not replace the need to assess fires involving paper, packaging, furnishings or other combustible materials.

CO₂ has limits. It provides little cooling, so a fire involving hot material may reignite. Discharging CO₂ in a small, poorly ventilated space can also create a risk to people, and the discharge horn can become extremely cold. Staff should be trained on the equipment provided and should never put themselves at risk to save property.

Which Types of Extinguisher Can Be Used Around Electrical Equipment?

Some water-based extinguishers carry a label showing that their discharge passed an electrical conductivity test. That marking has a specific meaning; it does not make every water-based extinguisher an appropriate choice for a live electrical hazard. Current BS 5306-8 guidance calls for non-conductive extinguishing media to be specified for live electrical equipment. If your site has water mist or another specialist unit, have a competent person check its exact approval and intended use.

Is an Electrical Fire a Class E Fire in the UK?

No. “Class E” is sometimes used informally, but it is not one of the standard UK fire classes used to identify what is burning. Electricity is an additional hazard because the equipment may be energised. The burning material still determines the fire class.

For example, an overheated appliance could ignite plastic casing or nearby paper. Cutting the electrical supply, where safe, removes the electrical hazard, but it does not necessarily put out the burning material. That is why the fire risk assessment must consider both the equipment and the surrounding fuel when choosing extinguishers.

What Should You Do If Electrical Equipment Catches Fire?

1. Raise the alarm and start the evacuation procedure. Warn others and make sure the fire and rescue service is called.
2. Keep clear of the equipment. Do not touch burning equipment, damaged cables or a switch that cannot be reached safely.
3. Isolate the electrical supply only if safe. Equipment can remain energised even when it appears to have been switched off. Do not delay your escape to find an isolator.
4. Only consider an extinguisher if workplace procedures allow it. The fire must be small, the extinguisher suitable, the person trained and the exit route clear.
5. Leave immediately if there is any doubt. Smoke, a spreading fire or an uncertain power supply are reasons to evacuate, close doors where safe and wait for the fire and rescue service.

An extinguisher is provided for an early-stage incident. It is not a reason to remain in a dangerous area or try to protect equipment at the expense of personal safety.

How Should a Business Choose and Position Extinguishers for Electrical Risks?

The starting point is the premises’ fire risk assessment. It should identify the electrical equipment and other fire hazards, who may be affected, how people will escape and whether suitable first-aid firefighting equipment is needed.

When reviewing extinguisher provision, consider:

• The actual hazard: small office appliances are different from switchgear, production machinery or a specialist plant room.
• What else could burn: packaging, furnishings, flammable liquids or other nearby materials may require additional extinguisher types.
• Accessibility: a suitable extinguisher should be visible and reachable without moving towards the hazard or blocking an escape route.
• The room: an enclosed or occupied space may affect whether CO₂ or powder is appropriate.
• Training: nominated staff need to know which extinguisher is provided, what it can be used on and when to evacuate.
• Maintenance: extinguishers need to remain in their intended position and be kept in working order.

The Regulatory Reform (Fire Safety) Order 2005 requires appropriate firefighting equipment where necessary for the safety of people, and a suitable system of maintenance for equipment provided. BS 5306-8:2023 gives detailed guidance on selecting and positioning portable extinguishers; BS 5306-3 addresses commissioning and maintenance.

If you are fitting out a new workplace or are unsure whether existing units match the risks, a fire extinguisher survey can identify gaps before new equipment is selected.

Does a CO₂ Extinguisher Cover Every Electrical Fire?

No. A CO₂ extinguisher is a common provision for ordinary electrical equipment risks, but its suitability depends on the whole incident. It may suppress flames without adequately cooling burning materials, which can lead to reignition.

Lithium-ion battery incidents need separate consideration. A battery entering thermal runaway can produce intense heat, hazardous gases and repeated ignition. A CO₂ extinguisher provided for a standard electrical cabinet should not be assumed capable of controlling a burning e-bike battery, battery storage system or electric vehicle. Such risks need a specific assessment and emergency plan.

Choosing the Right Equipment for Your Site

The practical question for an employer is not simply “Do we own a CO₂ extinguisher?” It is whether the right equipment is available in the right place for the risks identified, and whether staff understand when to use it.

Velocity Safety supplies, positions and commissions fire extinguishers for workplaces across the UK. We can review your electrical and general fire risks, recommend suitable extinguisher types and provide installation records for your fire safety documentation.

Electrical Fire Extinguisher FAQs

What colour is the extinguisher used for electrical fires?

A CO₂ extinguisher has a black identification panel on its red body. Check the label rather than relying on colour alone: it identifies the extinguishing medium, instructions and relevant fire ratings.

Can you use a water extinguisher on an electrical fire?

Do not assume a standard water extinguisher is safe for live electrical equipment. Some specialist water-based extinguishers carry electrical test markings, but their permitted use is specific. The employer should specify suitable equipment based on the fire risk assessment and current guidance.

Can you use a powder extinguisher on electrical equipment?

Suitable non-conductive powder can be used for electrical risks. However, its discharge can reduce visibility, affect breathing and contaminate equipment. This makes powder a poor default choice for many occupied indoor spaces.

Should you switch off the power before using an extinguisher?

Electrical equipment should be disconnected or isolated before an extinguisher is discharged onto it, if that can be done safely. Never touch damaged equipment or put yourself in danger to reach a switch. Some equipment may remain live even when it appears to be off.

Are CO₂ extinguishers suitable for lithium-ion battery fires?

Do not assume so. A lithium-ion battery in thermal runaway presents a different risk from an ordinary electrical equipment fire. Battery charging and storage hazards should have their own fire risk assessment and emergency arrangements.

Is an electrical fire called a Class E fire?

“Class E” is an informal label sometimes seen online. In UK fire classification, electricity is treated as a hazard associated with the fire rather than a separate class of burning material.

Sources and Further Guidance

• BAFE: Extinguisher selection for live electrical equipment
• Fire Industry Association: BS 5306-8:2023 and electrical equipment
• GOV.UK: Making small non-domestic premises safe from fire
• HSE: Construction fire safety and extinguishers
• Regulatory Reform (Fire Safety) Order 2005